Chemical Properties of Element 105 in Aqueous Solution: Back Extraction from Triisooctyl Amine into 0.5 M HCl

Abstract

Previous studies of the halide complex formation of element 105 and its anion exchange with triisooctyl amine (TIOA) were continued. The experiments were performed on a one-minute time scale with the computer-controlled liquid chromatography system ARC A II on a mixture of 34-s ²⁶²Ha and 27-s ²⁶³Ha produced in the ²⁴⁹Bk(^lsO,5n) and ²⁴⁹Bk(¹⁸0,4n) reactions at a beam energy of 99 MeV. The Ha isotopes were detected by measuring the spontaneous fission and a-activities associated with their decay, and the a-decays of their daughters, 4-s ²⁵⁸Lr, and 6-s ²⁵⁹Lr. Time-correlated pairs of parent and daughter a-particles were also registered. ^262,263Ha was absorbed on the TIOA columns from either 12 M HCl/0.01 M HF or 10 M HCl, and was subsequently eluted in 0.5 M HCl/0.01 M HF like its homolog niobium, and the pseudohomolog protactinium, and unlike the closest homolog, tantalum, which remains in the amine phase under these conditions. The effluent was divided into an early Pa fraction and a subsequent Nb fraction. By varying the cut between the Pa fraction and the Nb fraction in rough steps, it was shown that the elution of element 105 occurs closer to the Pa elution position, i.e., earlier than the elution of Nb. These results confirm the non-tantalum like behavior of element 105 in 0.5 M HCl/0.01 M HF, and corroborate previously suggested structural differences between the halide complexes of element 105, niobium, and protactinium, on the one hand, and those of tantalum on the other hand.